TestInvoice.py

import pytest
from Invoice import Invoice

@pytest.fixture()
def products():
    products = {'Pen':{'qnt':10,'unit_price':3.75,'discount':5},
                'Notebook':{'qnt':5,'unit_price':7.5,'discount':10}}
    return products

@pytest.fixture()
def invoice():
    invoice = Invoice();
    return invoice

def test_CanCalculateTotalImpurePrice(invoice,products):
    invoice.totalImpurePrice(products)
    assert invoice.totalImpurePrice(products) == 75

def test_CanCalculateTotalDiscount(invoice,products):
    invoice.totalDiscount(products)
    assert invoice.totalDiscount(products) == 5.62

def test_CanCalculateTotalPurePrice(invoice,products):
    invoice.totalPurePrice(products)
    assert invoice.totalPurePrice(products) == 69.38